Oxidation of hydrocarbons



NOV. 4, v1952 p, C, KEN-H 2,616,898

y OXIDATION 0F HYDRoCARBoNs' Filed'neo. 8, -1948 3 sheets-sheet 1 ...nFS R V D O 8. E 4 f V C. w Nif T B a 2,.. A A 49 7 \M M7/jaa l 2 l if? um:lwlllhlfn N |r ||w\ I.. \6 n. DI. l' l I l l l 2 B 1| 4 .nl m f mIIIIIIIIIIIIIIIH nil IIIJJ/ OA f 3 8 Q mA y I. 2 6 Il. 9* 4 A A 1 3 l. r2 C.. SM/ 4 m 4` 4 d 4T 4 6 y 5 2 4 IIMWF 4 a Na 1.., II'P 1. y, m O N EF am# u l .M /4 5 w Nov. 4, 1952 P. c. KEITH 2,616,898

oxIDATxoN oF HYDRocARBoNs Filed Dec 8' 1948 sheets-sheet 2 #i A v l\ IZt 8b f CYCLONES WATER REACTOR` I7b feb qCU RESADUAL COPPER I4* GASESoxmgs SCRUBBEQ 2l -n l, HOPPER FORMALDEHYDE AIR Y SoLuTaoN 4b) sbl *8*oxfDlzER Renueva METHANE 7- 9 VGmNDEra 0 @Vo slzma INVENTOR Percfvaf C.fei/L ms: mw

ATTORNEYS P. c. KEITH OXIDATION oF HYDRQCARBONS Ngv, 4, 1952 3Sheets-Sheet 3 Filed Dec. 8, 1.948

AM NwgOn-m INVENTOR Percival C. feh B {5.}1

ONEYS ATT Patented Nov. 4, 1 952 OXIDATION oF HYDaocARBoNs Percival C.Keith, Peapack, N. J., assignor to The M. W. Kellogg Company, JerseyCity, N. J., a corporation of Delaware Continuation of applicationSerial No. 440,270,

April 23, 1942. This application December 8, 19458, Serial No. 64,180

5 Claims. (Cl. 260-342) The present invention relates to improvements inchemical conversions involving the contacting of a reactant in thegaseous or vapor'v phase with particles cfa solid contactagent. Thisapplicaa method which may be'practiced on a large commercial scale and'with commercially available equipment and under prevailing commercialoperating conditions.

tion is 'a continuation of my prior application 5 One ofthe features ofthe invention -resides in S. N. 440,270, led April 23, 1942, nowabandoned. the provision of the solid 'contact material in the Theinvention, although not limited thereto, is conversion zone inrelatively high concentrations. especially well exemplified andadvantageous in In certain aspects, the invention particularly itsapplication to the production of intermediate contemplates theintroduction of Vparticles of stage conversion products in satisfactoryyields contact material of controlled settling characand lquality byreactions, both organic and inorganic, which proceed successivelythrough several stages, but normally pass through such stages, due tothediiculty of temperature control or other reasons/at such a rate thatultimate conversion products are inevitably produced of relativelylittle or no value. Certain hydrocarbon conversion reactions areillustrative of such 'reactions and are particularly contemplated inthepractice of the invention. Such hydrocarbon conversion reactionsinclude the oxidation of hydrocarbons, including the light and normallygaseous aliphatic hydrocarbons, to intermediate oxidation products suchas alcohols, aldehydes, ketones and organic acids and the partialoxidationof aromatic hydrocarbons to such products as -rnaleic acid,benzoic acid, phthalic anhydride, and the like. The process is likewiseapplicable to inorganic reactions exemplilied by the conversion ofhydrochloric acid to chlorine by catalytic oxidation. Also, the processmay be applied tothe decomposition of light hydrocarbons such as ethane,`and butane to intermediate decompositionproducts such as acetylene,butene and butadiene. l

The particles of solid contact material utilized in the 'process' in itsvarious embodiments may function severally orf-jointly in any one ofseveral modes, either as a solid reactant which undergoes chemicalinteraction with the gaseous component, as a catalyst to accelerate thereaction in the desired direction, or as a means to control physicalconditions such as temperature within desired limits. Further, incertain instances one or more of these functions may be performed by asolid contact material containing a single component, or the solidcontact material may comprise two or more separate components each ofwhich performs one or more of these functions.

One of the important objects of my invention is the vprovision of Vaprocess wherein the temperature of the conversion Zone 4may, be readilycontrolled within desired limits ,for the purpose of producingsatisfactory yields and qualities of intermedite conversion products ofthe type above described. A'further object is the provision of Yteristics and yin controlled amounts into a reaction zone and theflowing of the reactant in the vapor phase upwardly through said Zone ata velocity adapted to produce a highly turbulent and dense pseudo-liquidphase of the solid particles whereby temperature control within desiredlimits is greatly facilitated and various other advantages' attained. Incertain other aspects, the invention contemplates a cyclic operationwhereby continuous operation is accomplished by circulating the contactmaterial successively through a conversion zone and thence through arevivication zone, either or bothof the zones containing therein adense, highly turbulent phase of solid particles.

Heretofore, it has been proposed to carry out chemical reactions underconditions adapted'for intermittent or batch operation, and according toa procedure involving passing an aerifor'm iluid upwardly through asubstantially stationary mass of confined, substantially uniformlysizedgranular particles of the order of 1A; inch or more in diameter, at sucha rate that the particles assume limited freedom of movement, and areplaced in vibrant motion by, but are not entrained,` inthe aeriform uid;The present process, while bearing some resemblance to this heretoforeproposed process, differs Atherefrom in a number of 'important andessential aspects. The dense pseudo-liquid phase of solid particlesutilized in the 'present process is characterized by thel extremerandom' and1 'circulatory' movement of the individual particlesthroughout theentire mass. This phenomenon is not due to a temperaturedifferential betweenthe particles in the various parts of the mass sinceit exhibits itself in a system wherein no such differential exists. Afurther feature of the process resides in the utilization of relativelyfinely divided particles, either partiallyor entirely to form thesolid'component of the dense, highly turbulent pseudoliquid phase. Thisphase preferably comprises or may even consist entirely of particles ofsuch a degree of neness that their free settling rate is suciently lowto'permt themY to be entrained l and carried out ofthe reaction-zonewith the upwardly flowing gaseous component even at the relativelylow velocities contemplated by the process. A further feature of theprocess resides in the preferred utilization of a mixed range of sizesin preference to :uniformly sized particles.

Pursuant to the present process, after the dense, highly turbulent phaseof solid particles is initially established to a desired depth or levelin the reaction zone, additional quantities of solid particlespreferably are continually addedth'ereto at a rate at least as greatasthe Arateat which particles are carried out overhead intrue entrainmentin the gas. The turbulent pseudoliquid phase may be established initallyby introducing the particles of solid contactmaterialinto the reactionzone through which the lgaseous component is fiowng upwardly at arelatively low velocity, in quantities and at a rate greater than that awhich the gaseous component is capable of carrying particles upwardlyout .of the *.zone in true .entrainrnent- .Due to -thispexcess loadingand lto the extent thereof, the desired pseudoliquid phase is graduallybuilt-.up in the conversionzone. The position of the upperlevel of thedense phase and hence the depth of this phase may be controlled by anyone of the several procedures. For example, after the level has reachedany particular horizontal plane it may -be stabilized in thisAposition-by decreasing the quantity of solid particles initiallyintroduced, and by thereafter adding them .in amount-exactlycorresponding lto the rate at `which the particles are carried out ofthe reactor in true `entrainment in the gaseous component. By la secondmethod, the :level is stabilized at the desired height by withdrawingsolid particles directly from the dense turbulent Vphase at a ratecorresponding to the quantity added in -excess of that capable of beingcarried out of the reaction zone in true entrainment. :By a thirdmethod, `the height of the Alevel'is predetermined by suitabledimensioning of the height of the reaction vessel. This third .method.is based on the `fact that as the dense turbulent mass is allowed tograduallybuild up .beyond a certain maximum height, the .quan- L tity ofmaterial carried out overhead through the high velocity gas outletgradually exceeds that capable of being carried-in true entrainment andfinally the level rises to a height Aat Awhich solid particles arecarried out overhead through thehigh velocity outlet at the same rate atwhich particles are added. It has been found that under such conditionsthe level of the dense phase valways occurs at a fixed distance belowthe high velocity outlet and accordingly the vdepth of the denseturbulent .phase may be maintained lat any desired value by initiallydesigning the reaction vessel to asuitable height, When employing thisthird method, thelevel may be further vadjusted by projecting the :highvelocityfgas outlet downward into the reaction zone to .any desireddistance, thereby v.reducing it from the maximum fixed by the overallheight of the reaction vessel to any desired minimum. The apparentanomaly of this condition, wherein the loading of Asolid particles inthe low velocity 1zone intermediate the .upper dense phase level and theopening to the high velocity outlet is -in excess of the loadingpossible -underftr-ue entrainment conditions, is explainable on the-basis that the additional lifting effect is due to the additionalenergy or work .supplied to the system by the displacing action of addedsolid particles in excess of -that loading-capableof being 'carried intrue -ientrainment in .the gas. The `ifxuf.-=e1,1.

trainment loading is essentially determined, other conditions beingconstant, by the particular velocity of the gas.

Various suitable modes of practicing the invention, and.its-'application to y.particular chemical reactions, are described.hereafter for the purpose of illustration only, including the con-:version of hydrocarbons to intermediate oxidation products pursuant totwo different embodiments, one lwherein the solid contact materialinteracts chemically with the gaseous component or components, fandanother wherein this mate- ,rialgfunctions'primarily as a catalyst.

The direct oxidation of hydrocarbons to the oxides ofcarbon Jand wateris, as is well known,

readily accomplished. Also well known is the fact that the oxidationoccurs stepwise, the rst step involving the formation of oxygenatedorganic intermediates such as alcohols, aldehydes, matones, organicoxides, esters, etc., which are of ,more value than the ultimateproducts of oxidation, namely, oxides of carb-on and water. Heretoforemany proposals .have been made Vdirected toward control 0f theoxidationreaction so that it would stop at the desired intermediateconversion product. However, all of these procedures have seriousdisadvantages. There are three chief sources .of difficulty in carryingout such conversions, namely, (1) the high temperature necessary toinitiate the oxidation, (2) the highly exothermic nature of theoxidation .reactions, and (3) .the fact that the desired intermediateconversion products are morereadily oxidized than the hydrocarbons fromwhich they were derived. The provision of a process whereby thesedeficiencies are largely obviated is an outstanding feature of thepresent invention.

In the drawings Fig. 1 illustrates diagrammatically a suitablearrangement of apparatus and process flow capable of general applicationfor practicing the invention by an embodiment involving a continuouscyclic process.

Fig. 2 illustrates diagrammatically a suitable arrangement of apparatusand process flow for practicing the invention as applied rto the partialoxidation of hydrocarbons by a catalytic process, as for instance theconversion of a mixture of methane and air to formaldehyde over acatalyst comprising copper oxide.

Fig. 3 illustrates diagrammatically a suitable arrangement of apparatusand process flow for the practice of the invention as applied to theproduction of oxygenated hydrocarbon by interl action of hydrocarbonsand metallic oxides, as

for example the production of formaldehyde by chemical interactionbetween methane and copper oxide.

Fig. Ai is .a sectional view taken alongthe line 4 4 of Figure 1.

Referring to Fig. 1, a suitable reactant or reactants in the gaseous orvapor phase, is vintroduced into the system through line 4 to reactorinlet line 3. A finely divided powdered solid contact agent isintroduced from line 2 at a suit-- able rate regulated by valve 46 intoa stream of the feed vapors ltraveling at a relatively high velocitythrough the reactor inlet Vline 3. The solid contact agent land vaporousre-actant may in certain cases .be heated prior to their mixture in line3. The contact agent thus introduced is picked up by the vaporousreactant and carried therewith fthrough `line 3 and introduced into .theflower part ,of reactor 6.

Reactor 6 isa vesselinthe form of a cylinder or other suitable shape;having a relatively large cross-sectional area comparedywith the'crosssectional 'arearof` the vapor inlet line 3,' and these relativeproportions cause a corresponding reduction in the velocity of thevapors after their passage from inlet line 3 into the reactor. Sincethegas travels through line 3 at a relatively high velocity; it isVcapable of carrying a loading of the solid particles much greater thanthe loading-'of such particles which may be carried in true entrainmentat the relatively low gas velocity maintained in reactor .6.' Thequantityv of particlesgintroduced through line 2 in excess of thismaximum true entrainment loading gradually accumulates in the reacatorto produce the desired highly'turbulent, pseudo-liquid phase aspreviously described.' When the upper'level of this' phase hasxreached adesired height, indicated by dottediline 1, it may be held substan#tially constant by withdrawal of solid particles through a=suitableoutlet 9 opening directly into the dense phase at a rate correspondingtothe amount added in excess of the true entrainment loading 'at the;gas velocity maintainedin the reactor, as previously described. Thelevel may also be stabilized at the desired position by decreasingr thequantity of particles added tothe dense phase/through line 2 and othersources, to a rate corresponding to said true entrainment loading.Ifneither of these expedients is employed, the level will gradually riseto a fixed maximum distance below the high velocity outlet 8, and thequantity of solid particles traveling throughr the intermediatesolid-gas disengaging zone B in excess of the true entrainment valuewill 'gradually increase during this upward rise of the level untilsolid particles are withdrawn from the system at the same rate at whichthey are introduced to the reactor. Since the height of the level inthis instance is a1- ways a fixed distance from the high velocity outlet8 (the particular distance being fixed by the constants of the system),it may be depressed from the maximum to any desired minimum height ofprojecting the outlet 8 downward into the reactor` toa distancecorresponding to the desired reduction in depth of the dense phase.

The highly turbulent and circulatory motion of the solid particles inthe dense phase produced, asabove described, results in the maintenanceof a substantially uniform temperature throughout the dense phase zoneand the lack of a decided temperature gradient therein, regardless ofthe fact of whether heat is developed or absorbed lby athe particularconversion involved. This turbulent movement further assures asubstantial homogeneous composition of the solid particles throughoutthe dense phase, regardless of any progressive change which occurs inthe individuallparticles during the conversion. 'I'he optimumfvelocitywith respect to its minimum and maximum value will be dependent upon thedensities, sizes and shapes of the solid particles employed, fand forany particular set of conditions this "velocity is preferably adjustedso as to maintain the desired highly vturbulent dense phase condition.For example, employing a finely divided powdered contact agentconsisting of a range of mixed size particles, all or most of.

which are'smaller than 100 microns, a gas veloc ity within-the range ofabout 1.0 to 2 ft. per

second is regarded as preferable. The minimum velocity for afmelypowdered contact agent conf sisting predominately of particles smallerthan 100 g microns "normally will exceed about.0.5 fft.

per'second in order -to maintain the desired degree of turbulence. Theforegoing` i' numerical values are illustrative of suitable` relationswhen utilizing solid particles havinga density corresponding to that ofclay, anda gas having a viscosity similar toair.' l A suitable inert gassuch as steam or the like is preferably introduced in the lower portionof the catalyst withdrawal passageway 9y through line I0 to displace orstrip conversion product vapors mixed with or adsorbed on the withdrawncontact material and to maintain it in aerated owable condition. Thecontact materialis withdrawn from passageway 9 through al standpipe IIto which an inert aerating mediumis Vsupplied lby means of inlet linesI2 distributed at Vsuitable intervals along the standpipe I I tomainy.tain the catalyst flowing `throughinV a state wherein itapproximates a liquid with'respect 'y cycle stream may-be withdrawnthrough a standpipe Ila similar to II andrecycled byway of linevdathrough a heat exchanger or cooler 26 and back to the dense phase zone Afor the purpose lof temperature control therein. Part of the gaseousfeed may be introduced throughline 21 to pick up the contact materialdischarged from standpipe I Ia and convey it throcgh line' 4a.

In vpracticing theprocess with apparatus such as shown in Fig. 1 andutilizing an outlet opening directly into the dense phase-forwithdrawing solid particles separately from the-gaseous component suchasoutlet 9, the preferred procedure is to maintain the'upper level 1sulciently low to provide an ample solid-gas disengaging` space Bintervening between the high velocity outlet 8 and the upper level ofthe dense phase toreduce the quantity of solids `carried overheadthrough outlet 8 toa minimum value, that is, a value corresponding tothel maximum trueentrainment loading at the relatively low velocitiesmaintained in zonev B. This procedurehas the advantage of reducing thequantity of solidparticles which must be eventually recovered from thereaction vapors to a minimum amount with a'consequent reduction in sizeand Vcost of the recovery equipment.' However, it will be apparentthatthe relative proportion of material Withdrawnthrough outlet 9 maybevaried within wide limits from a maximum as in the normallypreferredcase indicated above to a zero value as in thecase when valveI8 is closed (or outlet 9 omitted) and solid particles are withdrawnoverhead through line 8` at the same rate at which they are introduced.

The gaseous `conversion products withdrawn through outlet 8 maybe passedthrough any suitable type offgas solid recovery system for theseparation of the solid particles entrained therewith. As shown, thissystem may'suitably comprise a series of cyclone separators I3 and I 4through which the gas mixture is successively passed at a high velocity.Separated solidlparticles withdrawn from the bottom of the cyclones maysuitably be returned-to the dense phase zone A through 'the cyclone tailpipes 28 and 29. After 7 ment such as an absorber, scrubber,Afractionating tower, or the like.

In instances-wherein the used or spent contact material iscirculated ina cyclic process between a conversion `zone and va Vrevi'viiicationzone, suitable provision is made for any difference in pressure-b'etwe'en these Zones and the points of withdrawal and points ofintroduction of the catalyst. In the vsystem shown, the pressure at thebottom of standpipe I I includes the pressure head` provided by vtheaerated material in the standpipe, the head of contact material in zoneA and the static pressure in zone B in excess of atmospheric pressure.Standpipes II, I Ia and other similar outlet standpipes, are made of asuitable 'height to largely or entirely compensate for 'pressuredifferential between vthe point of withdrawaland point of introductionof the contact material.

The process .flow and apparatus utilized in the regeneration stage maybe substantially similar, as illustrated, to that 'shown and describedwith respect to the conversion stage. Dependent upon the particularchemical conversion involved, the reaction involved in one of thesestages may be exothermic, fand endothermic in the other stage, for viceversa, or both stages may be either exotherxnic or -endothermiciii-character, and to varying degrees. Dependent upon the particularrequirements of the conversion involved, the heat exchangers 22 and 2limay be operated either as coolers or .heaters for the recycle stream ofcontact'material and the quantity of recycle material is varied pursuant`tothe heat requirements of the system. Likewise, either stage mayreadily be operated ata pressure diiierent from that utilized in theother stage by utilizing standpipes such as standpipes I.I and =2 of asuitable height to `'balance the pressure differential involved.

From lthebottom of standpipe 'Il used contact material is fed under theinfluence of this pressure to a suitable feeding means such as valve I8'into inlet line I9 leading to the revivification zone. Used catalystthus introduced is mixed with air or other suitable revivifying mediumintroduced into line 'I9 vby line 2U.

The mixture of used contact material fand carrying medium lflows throughline I 9 into 'the 'bottom inlet hopper B of the regenerator V2 I-. Incertain cases lit may be mixed with a stream of recycled contactmaterial withdrawn from heat exchanger or cooler 22. Operatingconditions in the revivication zone may be suitably regulated withinlimits to vprovide a condition similar to that maintained in theconversion zone with respect to providing a dense 'turbulentpseudoliquid phase of the solid particles. During the course of thetravel or' the used contact 'material through the revivific'ationchamber, it is restored to a condition suitable for reuse in theconversion zone. -Reviviied contact material maybe withdrawn directly'from the dense phase zone A vby means of a withdrawal passageway orp'assageways opening directly into this zone. In the embodiment shown,two -such passageways 23 and 24 extending a substantial distance up zoneA' are provided. Outlet 23 serves vfor'the withdrawal of regenerated-contact material which is recycled 'by means of standpipe 43 and line55 through a heat exchanger or cooler 22 through which a cooling orheating medium is circulated by lines Y60 and 6I and thence back to theregenerator 2| for temperature control therein. Air or other suitableregenerating medium is supplied to line iithroughl'ine 62 to-convey thesolid 8 material discharged' through valve 41 through the exchanger 22.Outlet 24 serves for the Withdrawal of regenerated contact materialwhich is forwarded to the conversion system through standpipe 2.

Gaseous revivication products containing a relatively small proportionof the total contact material introduced into the revivii'lcation zonethroughline I9 are withdrawn by outlet pipe 25 and passed through asolid-gas separating system I 3a and I4a similar to elements I3 and I4and the contact material thus recovered is returned to the dense phasezone A or to any other suitable point in the system.

The height Vof the upper level in the dense phase of zones A and A isdependent upon the total quantity of contact material circulated in thesystem which quantity may be-varled by withdrawal' of contact materialfrom the system through valved line 49 to storage when klowering of thelevel is desired and by the addition of contact material to the systemthrough line 49 when raising of the level is desired. The relativeheight of the level in zone A to that of zone A is controlled for a xedquantity of contact material by suitable regulation of the dischargerates through valves I8, I8a, 46 and 41.

It will be apparent to those skilled in the art, from the foregoingdescription, that the procedure described with reference to Fig. l maybe advantageously applied to a wide variety of chemical reactionsinvolving the contact of a reactant in the vapor phase with particles ofa solid contact agent, either in a single stage or by a cyclic processinvolving an alteration of the characteristics oi the particles ofcontact material in one stage, such as a conversion stage, and therestoration of these characteristics in a second stage, as for exampleby a regeneration treatment. The solid contact material may be selectedfrom a class of material adapted to act either, (l) as a solid reactantwhich undergoes chemical interaction With the component in the vaporphase, (2) as a catalyst to accelerate the reaction in the desireddirection, (3) as a means to control physical conditions, such astemperature within the desired limits, or (4) as a means to perform acombination of two or more of these functions. Further, the solidcontact material may consist of a single type of component or it maycomprise 2 or more separate components, each of which performs one ormore of the enumerated functions.

The process is especially advantageous as applied to the production ofintermediate stage conversion products by reactions which proceedsuccessively through several stages, but under uncontrolled conditions,pass through such stages, due to the diiculty of temperature control atsuch a rate that ultimate conversion products are produced of relativelylittle value. The partial oxidation of hydrocarbons exemplies this classof reactions; for example, the conversion of a normally gaseoushydrocarbon such as methane to formaldehyde and the partial oxidation ofaromatic hydrocarbons such as nap-hthalene to phthalic anhydride.

Fig. 2 illustrates a suitable process flow and an arrangement ofapparatus for the catalytic oxidation of methane Ato formaldehyde inaccordance with the 4reaction represented by the following equation:

9j formaldehyde and water is exothermic to the extent of about 67,000calories per gram mol of formaldehyde produced at 1000 F., the lattertemperature representing an approximate preferred temperature ofreaction when either the oxide of copper or silver is employed as thecatalyst.

Elements of Fig. 2 corresponding in their general functions to similarelements in Fig. 1 are indicated thereon by corresponding referencenumerals with the subscript 1). An oxygencontaining gas such as air isintroduced into the system through line 4b. Finely divided particles ofa solid contact material such as particles of copper oxide or a mixtureof copper and copper oxide are introduced to the stream of air flowingthrough line 4b from hopper 9. Methane, or other suitable gaseousreactant, is supplied to line 3b through line I0. The dimensions of thereactor Iib and the quantity and character of the reactants introducedthrough line 3b are such as to provide a highly turbulent pseudo-liquidphase therein as previously described, an upper level for this densephase being indicated by dotted line lb. In the system shown, level Ibis preferably maintained at a suitable distance from outlet 8b so thatonly a relatively small amount of the introduced particles of solidcontact material pass out overhead with the gaseous conversion'productsfor ultimate recovery in the gas solid recovery system comprisingcyclones I I and I2. Gaseous conversion products including formaldehyde,unconverted methane and any additional side reaction products Withdrawnoverhead from cyclone I2 are passed to a suitable products recoverysystem such as a scrubber I4 by transfer line I3. In scrubber I4 thegaseous products are passed in counterow with a suitable scrubbingliquid such as Water, and are withdrawn and recovered as the desiredproduct from the bottom thereof in solution.

Residual gases are withdrawn from the top of the scrubber through lineI6 and may either be withdrawn from the system, or the unconvertedportion thereof may be recycled to the feed inlet.

Used catalyst particlesmay be continuously Withdrawn'from the reactorthrough outlet line I'I and rpassed to a-suitable revivification stageI8. In this particular case, the regeneration process may consist ofalternating oxidation and reduction treatments to restore the catalystparticles substantially to their original condition with-respect tosurface and particle size since the,V particles normally show a tendencyto sinter or agglomerate to larger particles during the conversion.

-From reviviflcation zone I8 the particles may be further subjected to asuitable grinding and/or sizing operation in zone I9, if necessary, toiurther reduce the particles to their original particlesiz'e. From zoneI9 the particles are recycled back to hopper 9 through lines 20 and 2|together with the particles withdrawn from the bottom portions ofcyclones II and I2.

' In the above ow each of the various components'may be suitablyintroduced through line 3b to the reactor at room temperature, and theturbulent pseudo-liquid phase inV the reactor thereby maintained at asuitable uniform elevated temperature, for example about 1000 F. Thepowdered copper oxide catalyst in the pseudoliquid' phase is in constantand rapid agitation and as aresult there is practically no temperaturegradient throughout the height of the reaction-space, despite the highlyexothermic character of the reaction. The gaseous components, air andmethane, at room temperature will absorb 10,000 calories in going fromroom temperature to 1000 F., thus leaving about 58,000 calories to beotherwise removed. Assuming copper oxide isthe catalyst employed, about2.5 lbs.\of the catalyst at room temperature may be added per mol ofmethane reactant, and the copper oxide thus added will absorb 58,000calories in going from'room temperature to 1000*' F., corresponding toabout 1.5 lbs./ catalyst per cu. ft. of gaseous reactants introduced tothe reaction zone. In the event that the recycled catalyst as Withdrawnfrom hopper 9 would otherwise be at a temperature above the desired roomtemperature, a separate cooler may be provided in line 20 similar inconstruction and purpose to exchanger 26 of Figure 1. Since normally itis preferred to operate with an excess of methane, or in the presence ofdiluent gas such as nitrogen or the like. the inlet loading of catalystparticles in the gas stream will usually be less than 1 lbpper cu. ft.of entering gas. As heat absorbent capacities of particular solids vary,the inlet quantity of catalyst must be adjusted in accordance with theparticular catalyst employed. In this particular example, the copperoxide constituting thersolid contact material has several functionssince the relatively large quantity of catalyst added is for the purposeof heat absorption as well as for catalysis. If desired, the quantity ofcopper oxide in excess of that required for catalysis may be replaced byparticles of a suitable inert solid, thereby utilizing a contactmaterial comprising two components to subserve the separate *functionsof catalysis and heat absorption.

Fig. 3 illustrates the application of the process to a reactioninvolving .the chemical-interaction of the particles of solid contactmaterial with the gaseous component, specically the production offormaldehyde by a reaction represented by the following equation:

Elements of Fig. 3, corresponding generally in their function tocorresponding elements of Fig.v 1, have been indicated by similarreference numerals with the subscript c and hence a detailed descriptionthereof is unnecessary. The above reaction is somewhat endothermic andaccordingly the required desired uniform temperature of the reactionzone, for example about 1000 F., may suitably be supplied by supplyingthe copper oxide to the'conversion zone at a higher temperature than theconversion temperature, for example a temperature of 1700'o F. Thecopper oxide is reduced to copper or a lower form of oxide in theconversion zone 6c and thereafter it is reoxidized in the regenerationzone 'I'c. i From the foregoing, it will be apparent that the process isgenerally applicable to chemical reactions requiring for theircompletion a change in the total heat energy content of the reactionsystem, that is, reactions of either an exothermic or endothermiccharacter. It will be evident that by the present process asubstantially uniform and optimum conversion temperature in theturbulent pseudo-liquid phase may be maintained by introducing theparticles `of solid contact material in such amount and at such atemperature level as to either absorb or add the heat requiredtomaintain the reaction at the desired uniform optimum level. Theparticles thus added may be supplemented byin part, or be entirelyconstitut- 1li ed by a stream of `particles.withdrawn from thepseudo-liquid phase and recycled thereto after passage through asuitable cooling and/or heating zone, as required. l

I claim:

1. A process for the conversion of hydrocarbons to intermediateoxygenated organic compounds which comprises passing in vapor form ahydrocarbon selected from the group consisting of normally gaseousaliphatic `hydrocarbons and the aromatic hydrocarbons having molecularWeights not higher than naphthalene through a irst passageway ofrelatively restricted cross-section at a relatively high velocityintoafirst enlarged reaction'zone containing finely divided contactmaterial comprising copper oxide as substantially the -sole oxidizingmaterial,v passing said hydrocarbon vapors upwardly through said firstIreaction zone at a relatively low velocity effective to maintain saidlcontact material 1 a-s 'a -relatively dense turbulent pseudo-liquidmass -having adefinite level therein-toform an upper solids-gasdisengaging zone, maintaining said 'rst reaction zone at an appropriatetemperature such that copper Y oxide reacts with said hydrocarbon toproduce intermediate oxygenated organic 'compounds and to substantiallyreduce the copper oxide and at which temperature the -finely dividedcopper oxide ismaintained'in a iiuidized `conditionfcontinuously-withdrawing intermediate-oxygenated organic compounds and reducedcopperoxide from said first reaction Zone,passing air through a secondpassageway of `relatively restricted cross-section at a relatively highvelocity into a second enlarged reaction zone containing reduced copperoxide, passing air upwardly through said second reaction zone at a,relatively low velocity effective to maintain said contact material as arelatively dense pseudo-liquid'mass having a definite level therein toforman upper solids-gas disengaging zone, maintaining said secondreaction zone under conditions such that the reduced copper oxide isoxidized, continuously withdrawing contact material Vcomprisingreoxidized copper oxide from said second reactionzone, introducing samey into Vsaid first passageway whereby reoxidized copper oxide isentrained in the hydrocarbon vaporstherein and passed to said rstreaction zone, and introducing reduced copper oxide withdrawn from saidrst reaction zone into said second pasageway whereby said contactmaterial is entrained in the air and passed to said second reactionzone.

2. A process for the conversion of naphthalene to phthalic anhydridewhich comprises passing naphthalene through a first passageway ofrelatively restricted cross section at a relatively high velocity into afirst enlarged reaction zone containing nely-divided copper oxide assubstantially the sole oxidixing material, passing naphthalene upwardlythrough said rst reaction zone at a relatively low velocity eiective tomaintain said copper oxide particles as a relatively dense turbulentpseudo-liquid mass having a deiinite level therein to form' an uppersolids-gas -disengaging zone, maintaining said first reaction zone at anappropriate temperature such that copper oxide reacts with naphthaleneto produce phthalic anhydride and to substantially reduce the copperoxide and at which temperature the finely divided copper oxide ismaintained in a fluidized condition, continuously withdrawing phthalicanhydride as a product of the process from said rst reaction zone,passing-air through a second passageway of relatively restricted crosssection at la relatively high velocity into .a second enlarged reactionzone containing finely-divided reduced copper oxide, passing airupwardly through said second reaction zone at a relatively low velocityeiective to maintain reduced copper oxide as a relatively denseturbulent pseudo-liquid .mass having a denite level therein to form anupper solids-gas di-sengaging zone, maintaining said second reactionzone under conditions such that reduced copper oxide is reoxidized,withdrawing reoxidized copper oxide from said second reaction zone andintroducing same into said first passageway whereby the copper oxide isentrained in naphthalene and passed to said rst reaction zone, andwithdrawing reduced copper oxide from said first reaction zone andintroducing same into said second passageway whereby reduced copperoxide is entrained in air and -passed to said second reaction zone.

3. A process for the conversion of methane -to formaldehyde whichcomprises passing methane through a first passageway of relativelyrestricted cross section at a relatively high velocity into a rstenlarged reaction Zone containing .finely-divided copper oxide assubstantially the `sole-oxidining material, passing methane upwardlythrough said first reaction `zone at a relatively low velocity effectiveto maintain said copper oxide Contact material as a relatively denseturbulent pseudo-liquid mass having a definite level therein to form anupper vsolids-.gas Vdisengaging zone, maintaining said first reactionzone at a temperature of -about 1000 to react methane with copper oxideto produce formaldehyde and substantially reduce copper oxide,passingair through a second passageway of `relatively restricted cross sectionat a relatively high velocity into a second enlarged reaction zonecontaining finely-divided reduced copper oxide, -passing air upwardlythrough said second reaction zone at a relatively low velocity effectiveto maintain said copper oxide as a relatively dense turbulentpseudo-liquid mass having a definite level thereinto form an uppersolids-gas disengaging zone, maintaining said second reaction zone underconditions such that reduced copper oxide is reoxidized, withdrawingreoxidized copper oxide from said second reaction zone and introducingsame at a temperature of approximately 1700" F. into said iirstpassageway whereby methane is preheated to the reaction temperature andreoxdized copper oxide is entrained and passed to said iirst reactionzone, and withdrawing reduced copper oxide fromsaid rst reaction zoneand introducing same into said second passageway whereby reduced copperoxide is entrained in the air and passed to said second reaction zone.

4. A process for the conversion of methane to formaldehyde whichcomprises introducingmethane into a first reaction zone containingnelydivided copper oxide as substantially the sole oxidizing material,passing gases upwardly through said first reaction zone at a relativelyloW lVelocity effective to maintain said lcopper-oxide as a relativelydense turbulent pseudo-liquid mass having a definite level'therein toY:form an upper solids-gas di-sengaging zone, maintaining `said iirstreaction zone atan appropriatetemperature such that copper oxide reactswith Vmethane to produce formaldehyde and to substantially 'reducecopper oxide and at which temperature the finely divided .copper'oxideis maintained in a fluidized condition,` withdrawing -Irom `the upperaciertos 13 portion of said rst reaction zone an efiluent containingformaldehyde and entrained reduced copper oxide particles, contactingsaid eiiluent with a stream of water to dissolve said formaldehyde andto remove said entrained reduced copper oxide, ltering reduced copperoxide from the resulting slurry, drying reduced copper oxide thusrecovered, and passing same together with air into a second reactionzone, passing gases upwardly through said second reaction zone at arelatively low velocity effective to maintain said contact material as arelatively dense turbulent pseudoliquid mass having denite level.therein to form an upper solids-gas disengaging Zone, maintaining saidsecond reaction zone under conditions such that reduced copper oxide isreoxidized,

rwithdrawing from the upper portion of said second reaction zone aneiiluent containing entrained reoxidized copper oxide, separatingentrained copper oxide from the effluent of said second reaction zone,passing a portion of said effluent after removal of reoxidized copperoxide therefrom to said first reaction zone, and introducing therecovered reoxidized copper oxide into that portion of the eiuent fromthe second reaction zone which is passed to the rst reaction zone.

5. A process for the conversion of methane to formaldehyde whichcomprises introducing methane into a first reaction zone containingnelydivided copper oxide as substantially the sole oxidizing material,passing gases upwardly through said first reaction zone at a relativelylow velocity effective to maintain said copper oxide as a relativelydense turbulent pseudo-liquid mass having a definite level therein toform an upper solidsgas disengaging zone, maintaining -said firstreaction zone at an appropriate temperature such that copper oxidereacts with methane to produce formaldehyde and to substantially reducecopper oxide and at which temperature the finely divided copper oxide ismaintained in a fluidized condition, withdrawing from the upper portionof said first reaction zone an eiluent containing formaldehyde andentrained reduced copper oxide particles, recovering reduced copperoxide from the eiiiuent from said rst reaction zone, and passing sametogether with air into a second reaction zone, passing gases upwardlythrough said second reaction zone at a relatively low velocity effectiveto maintain said contact material as a relatively dense turbulentpseudo-liquid mass having a denite level therein to form an uppersolids-gas disengaging zone, maintaining said second reaction zone underconditions such that reduced copper oxide is reoxidized, withdrawingfrom the upper portion of said second reaction zone an effluentcontaining entrained reoxidized copper oxide, separating entrainedcopper oxide from the eiiluent of said second reaction zone, passing aportion of said effluent after removal of reoxidized copper oxidetherefrom to said first reaction zone, and introducing the recoveredreoxidized copper oxide into that portion of the effluent from' thesecond reaction zone which is passed to the rst reaction zone.

PERCIVAL C. KEITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

Y UNITED STATES PATENTS Number Name Date 1,836,325 James Dec. 15, 19311,984,380 Odell Dec; 18, 1934 2,270,903 Rudbach Jan. 27, 1942 2,271,148Becker et al Jan. 27, 1942 2,304,128 Thomas Dec. 8, 1942 2,316,664Brassert et al. Apr. 13, 1943 2,360,787 Murphree et al. Oct. 17, 19442,382,296 Murphree et al. Nov. 7, 1944 2,373,008 Becker Apr. 3, 19452,378,531 Becker June 19, 1945 2,378,542 Edmister June 19, 19452,382,382 Carlsmith et al. Aug. 14, 1945 2,389,133 Brassert et al Nov.20, 1945 2,421,664 Tyson June 3, 1947 2,424,467 Johnson July 22, 19472,425,754 Murphree et al Aug. 19, 1947 2,425,849 Voorhees Aug. 19,194']l 2,498,088 Lewis et al Feb. 21, 1950 2,515,373 Keith et al July13, 1950 2,518,693 Jahnig Aug. 15, 1950 FOREIGN PATENTS Number CountryDate 559,080 Great Britain Feb. 3, 1944

1. A PROCESS FOR THE CONVERSION OF HYDROCARBONS TO INTERMEDIATEOXYGENATED ORGANIC COMPOUNDS WHICH COMPRISES PASSING IN VAPOR FROM AHYDROCARBON SELECTED FROM THE GROUP CONSISTING OF NORMALLY GASEOUSALIPHATIC HYDROCARBONS AND THE AROMATIC HYDROCARBONS HAVING MOLECULARWEIGHTS NOT HIGHER THAN NAPHTHALENE THROUGH A FIRST PASSAGEWAY OFRELATIVELY RESTRICTED CROSS-SECTION AT A RELATIVELY HIGH VELOCITY INTO AFIRST ENLARGE REACTION ZONE CONTAINING FINELY DIVIDED CONTACT MATERIALCOMPRISING COOPER OXIDE AS SUBSTANTIALLY THE SOLE OXIDIZING MATERIAL,PASSING SAID HYDROCARBON VAPORS UPWARDLY THROUGH SAID FIRST REACTIONZONE AT A RELATIVELY LOW VELOCITY EFFECTIVE TO MAINTAIN SAID CONTACTMATERIAL AS A RELATIVELY DENSE TURBULENT PSEUDO-LIQUID MASS HAVING ADEFINITE LEVEL THEREIN TO FORM AN UPPER SOLIDS-GAS DISENGAGING ZONE,MAINTAINING SAID FIRST REACTION ZONE AT AN APPROPRIATE TEMPERATURE SUCHTHAT COPPER OXIDE REACTS WITH SAID HYDROCARBON TO PRODUCE INTERMEDIATEOXYGENATED ORGANIC COMPOUNDS AND TO SUBSTANTIALLY REDUCE THE COPPEROXIDE AND AT WHICH TEMPERATURE THE FINELY DIVIDED COPPER OXIDE ISMAINTAINED IN A FLUIDIZED CONDITION, CONTINUOUSLY WITHDRAWINGINTERMEDIATE OXYGENATED ORGANIC COMPOUNDS AND REDUCED COPPER OXIDE FROMSAID FIRST REACTION ZONE, PASSING AIR THROUGH A SECOND PASSGEWAY OFRELTIVELY RESTRICTED CROSS-SECTION AT A RELATIVELY HIGH VELOCITY INTO ASECOND ENLARGED REACTION ZONE CONTAINING REDUCED COPPER OXIDE, PASSINGAIR UPWARDLY THROUGH SAID SECOND REACTION ZONE AT A RELATIVELY